This application claims priority from Korean Patent Application No. 2003-47413, filed on Jul. 11, 2003, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety.
1. Field of the Invention
The present invention relates to an image forming system, and more particularly, to a method and apparatus for controlling paper pickup in an image forming system by which the probability of paper jams caused by a pickup error of paper is reduced.
2. Description of the Related Art
In an electrophotographic image forming system, when an exposure unit radiates light onto a photosensitive medium charged to a predetermined potential, an electrostatic latent image is formed on the photosensitive medium. Thereafter, a developing unit forms a toner image by supplying toner to the electrostatic latent image. In general, a color electrophotographic image forming system needs four developing units in which four color toners, such as cyan (C), magenta (M), yellow (Y), and black (B), is stored. The toner image is transferred onto paper directly from the photosensitive medium or via an intermediate transfer medium. When the transferred toner image passes a fusing unit, the toner image is fused on the paper by heat and pressure. A single color or multiple color image is printed on the paper through the above procedure.
The above image forming system sets the number of re-attempts of pickup of paper at a time when a printing operation starts, and performs paper pickup by driving a pickup unit. When paper is not detected by a paper feeding sensor within a predetermined time period from a time when the pickup unit is driven to a time when front end of paper is detected by the paper feeding sensor, it is determined that a pickup error has occurred, and the image forming apparatus performs paper pickup repeatedly. The above paper pickup operation is performed by the set number of re-attempts of pickup of paper. When paper pickup does not occur successfully within the number of re-attempts of pickup of paper, it is determined that a paper jam has occurred, and the image forming system indicates a message representing that a paper jam has occurred, or generates a warning sound.
However, when a printing speed is fast, it is difficult to obtain a time required to re-attempt paper pickup when a pickup error occurs according to mechanical specifications of image forming systems, resulting in that it is difficult to set the number of re-attempts of pickup of paper. As a result, reducing the probability of paper jams by performing a paper pickup operation is not possible.